/Engine/Plugins/FX/Niagara/Source/NiagaraEditor/Public/ViewModels/NiagaraEmitterHandleViewModel.h
Gets a multicast delegate which is called any time a property on the handle changes.
[FOnPropertyChanged](API\Plugins\NiagaraEditor\ViewModels\FNiagaraEmitterHandleViewModel\FOnPropertyChang-) & OnPropertyChanged()